The present invention relates to generally a clamping device, and more particularly a three-piece shipping clamping device for use in clamping together an inner packing box and an outer packing box or a plurality of packing boxes.
In general, the packing bands or belts made of steel or synthetic resin have been used for binding the packing boxes. Therefore there is a fear that the packing bands or belts are loosened or cut off during the shipment. When the packing bands or belts are cut off, they cannot be reused.
There has been devised and demonstrated the packaging method in which the inner and outer boxes are bounded together by means of the clamping or locking devices attached to the peripheries of the boxes. However, when the clamping or locking devices are broken, the inner and outer boxes cannot be bond together even through they may be used.
There has been also proposed a two-piece shipping clamping device of the type comprising a male and female members. The male member has a large-diameter cylindrical portion with the closed bottom and the flange extended outwardly from the periphery of the open end and a small-diameter cylindrical portion extended from the bottom of the large-diameter cylindrical portion coaxially thereof. At the open end of the small-diameter cylindrical section are attached engaging projections which are angularly spaced apart by 180.degree. . The female member has a cylindrical barrel or drawn portion for receiving therein the small-diameter cylindrical portion of the male member, and flange extending outwardly from the bottom of the cylindrical barrel or drawn portion. A hole with diametrically spaced apart recesses for permitting the insertion of the engaging projections is formed through the bottom of the cylindrical barrel portion of the female member. In packing, the barrel portion of the female member is fitted into the hole formed through the side wall of an inner packing box, and the large-diameter cylindrical portion of the male member is fitted into the hole formed through the side wall of an outer packing box in alignment with the hole of the inner box, in such a manner that the small-diameter cylindrical portion of the male member is fitted into the cylindrical barrel portion of the female member and the engaging projections are inserted through the recesses of the hole formed through the bottom of the female member. Therefore, one holds a knob formed within the large-diameter cylindrical portion of the male member to rotate the latter through 90.degree. , thereby clamping together the inner and outer packing boxes. With the use of such clamping devices, the packaging may be much facilitated, but there is a defect that the male and female members cannot be fabricated by the drawing and punching operations because they are too complex in construction. Therefore, two kinds of dies or molds must be prepared with the result of the increase in cost.